Physics
Scientific paper
Dec 2003
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003agufmsm32b1159s&link_type=abstract
American Geophysical Union, Fall Meeting 2003, abstract #SM32B-1159
Physics
2431 Ionosphere/Magnetosphere Interactions (2736), 2481 Topside Ionosphere, 2483 Wave/Particle Interactions, 2736 Magnetosphere/Ionosphere Interactions, 2784 Solar Wind/Magnetosphere Interactions
Scientific paper
A vast research of radar and spacecraft observations and models has established that the magnitude of the ion flux of ionospheric origin is a consequence of an intricate relationship between the ionosphere and external forcing from the magnetosphere and the Sun. Ions that flow upward from the polar ionosphere fall into two categories: bulk ion flows with energies up to a few eV, and the suprathermal ion flows. Suprathermal ion flows include transversely accelerated ions, upwelling ions, ion conics, and ion beams. These flows have been observed at altitudes ranging from ~500 km to several thousand km. Different extraction mechanisms have been proposed to account for the suprathermal ion flux observed by spacecraft at different altitudes. However, it is still unclear how ions are accelerated with altitude in each region of the polar ionosphere for different external forcing conditions. Incoherent-scatter radar and polar orbiting spacecraft measurements have shown that prior to their extraction from the ionosphere, ions are energized locally at topside F region altitudes. The amount of energy gained in the ionosphere due to this preconditioning, however, cannot account for the magnitude of escaping fluxes observed at higher altitudes. The ion extraction process must be a combination of processes that couple the ionosphere source (the F region) to acceleration mechanisms at high altitudes. Simultaneous measurements of ion populations at different altitudes are useful to understand how the ion upflows evolve with altitude. We use conjunctions between Incoherent scatter radars and FAST to explore the height evolution of ion upflows. First, we explain how we define a conjunction in terms of spatial proximity, similarity of particle precipitation or lack of precipitation, and azimuthal extent of auroral precipitation at or adjacent to the topside F-region ion upflow measurement. Then we present the results of a group of conjunctions between FAST and the Sondrestrom and EISCAT radars to show how the efficiency of extraction of ionospheric ions (measured as the ratio of ion flux at FAST with energy of at least 10 eV and pitch angles of at least 90 degrees and bulk ion flux at the topside F-region) can vary from a few percent to several tens of percent, depending on the magnitude of various magnetospheric input parameters such as electron precipitation flux, convection, field-aligned potential drop, and Alfven wave amplitude.
Sanchez Ennio R.
Semeter Joshua
Stromme Anja
No associations
LandOfFree
Quantifying the Extraction Efficiency of Ion Upflows Using ISR-FAST-POLAR Common Volume Observations does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Quantifying the Extraction Efficiency of Ion Upflows Using ISR-FAST-POLAR Common Volume Observations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Quantifying the Extraction Efficiency of Ion Upflows Using ISR-FAST-POLAR Common Volume Observations will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1649398